With tower cranes in which the tower comprises one or more tower elements which are connected to one another in the vertical direction, the height of the tower can be increased by the use of further tower elements. However, tower cranes have a maximum free-standing hook height. If the latter is exceeded, the tower crane has to be fastened to the structure to be erected by a horizontal anchorage. The maximum achievable hook height can hereby be considerably increased.
It is possible with such tower cranes to have the tower crane grow with the structure by the installation of further tower elements, with the stability of the tower crane being ensured by one or more structural guying devices. A tower crane having such a structural guying device is already known from DE 20 2011 100 477 U.
Such tower cranes having a structural guying device are used, for example, for erecting wind power stations. When installing such wind power stations, the rotor blades have to be guided by the crane during the installation. The rotor blades are guided as standard by ropes from the ground during the installation. The rope tension forces which can be applied by such a ground guidance are very low so that only very small wind speeds can be permitted on such an installation. Furthermore, space problems often result in the guidance of the ropes from the ground if, for example, the wind power station is set up in a wood area in which the space relationships are very restricted in part.
It is therefore the object of the present invention to further develop a tower crane of the category such that long objects such as rotor blades can be guided in very high heights during the installation.
This object is achieved with the invention by means of a tower crane comprising a tower with at least one tower element and a structural guying device having at least one guying rod for a horizontal anchorage of the tower at a structure, wherein a guide frame is arranged vertically movably at the tower; wherein at least one positioning rope is adjustably fastened to the guide frame.
A tower crane accordingly has a tower composed of at least one tower element, in particular a lattice piece, preferably having a structural guying device which is anchored to a structure by at least one guying rod with respect to the horizontal and which has a guide frame which is vertically movable at the tower, with at least one positioning rope being adjustably fastened to the guide frame. The distance between the element to be guided, for example the rotor blade, and the guide point can be considerably reduced via this positioning part which is adjustably fastened to the guide frame so that the object to be mounted can be guided in a substantially more stable manner. The guide frame can respectively be vertically repositioned in height at the tower. Guidance can hereby takes place completely independently of the space relationships on the ground. Furthermore, an installation can also take place at comparatively higher wind speeds.
Preferred embodiments of the invention result from the dependent claims following on from the main claim.
The guide frame can preferably be vertically readjustable along the guide frame via at least one rope guide.
The at least one rope guide has a rope drum arranged at the tower and a deflection pulley arranged at a climb piece or at the guide piece. Two rope guides are preferably present for moving the guide frame and can be adjustable via a two-rope winch having two rope drums.
The guide frame is configured in U shape in accordance with an advantageous embodiment of the invention so that it engages around the tower at three sides.
To achieve an even higher stability and to prevent a lifting of the U-shaped guide frame from the tower, the U-shaped guide frame is preferably angled at its open end to engage around the corner regions of the tower.
The guide frame particularly advantageously has roller bearings or slide bearings in the corner regions of the tower and is supported thereon during the vertical upward and downward movement with respect to the tower. Since the weight of the guide frame is very high due to its stable design, the guide frame can be separable for the purpose of installation and transportation.
A winch is arranged at the guide frame for the adjustment of the at least one positioning rope. Two ends which are controllable independently of one another are advantageously provided for the independent adjustment of two positioning ropes.
In addition, telescopic struts can be arranged at the guide frame which serve, on the one hand, for guiding the positioning ropes and which serve, on the other hand, as dampers if a contact of the object to be guided, for example the rotor blade, and of the struts occurs.
In accordance with a particularly advantageous embodiment of the invention, the guide points for the positioning ropes provided at the guide frame are rotatable about the tower. Suitable guides are provided at the guide frame for this purpose.
The guide frame can additionally serve as a passenger elevator and/or goods elevator. However, two independent rope guides for a vertical displacement of the guide frame are required here for use as a passenger elevator.
A compensation weight is preferably provided for a weight compensation during the vertical movement of the guide frame, in a similar manner as is known from conventional elevator technology.
The invention furthermore comprises a method of mounting a wind turbine rotor blade to a wind turbine rotor hub using a tower crane comprising a tower with at least one tower element with a structural guying device having at least one guying rod for a horizontal anchorage of the tower, wherein a guide frame is arranged vertically movably at the tower, and wherein at least one positioning rope is adjustably fastened to the guide frame; wherein the rotor blade is aligned with the positioning ropes starting from the guide frame.
Further details, features and advantages of the invention result from the embodiments shown in the enclosed drawings.